What is a Normal Red Blood Cell Count?

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  • Written By: Jessica Ellis
  • Edited By: Bronwyn Harris
  • Last Modified Date: 25 March 2019
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A red blood cell (RBC) count measures that amount of red blood cells in a sample and makes an overall estimate of the average count in a person's blood. These numbers are expressed in either million per microliter (uL) or million per millimeter cubed. This information may be very important in diagnosing a variety of conditions that are characterized by an abnormally low or high count.

A normal red blood cell count will vary depending on the age and sex of the person tested. The normal number for women tends to range from about 4.2-5.4 million red blood cells per microliter (million/uL). Men have a considerably higher normal range, falling between 4.7-6 million/uL. Children tend to fall somewhere in the middle of these two, and have a very narrow normal red blood cell count range of about 4.6-4.8 million/uL. Since red blood cells are essential in the movement of oxygen throughout the body, people who live at higher altitudes, where oxygen is thinner, may have a slightly higher normal range.


Having a normal number of red blood cells helps the body perform nearly every function involved with survival. The hemoglobin of RBCs is believed to transport about 98% of the body's oxygen, carrying it to and from organs like a very efficient delivery truck. When a RBC count is too low, creating a condition known as anemia, the body is at risk of not receiving sufficient oxygen, which may cause a variety of problems including organ damage. A high red blood cell count, known as polycythemia, can also be bad news; heart, lung, and blood diseases are all associated with an abnormally high RBC.

Symptoms of a lower than normal red blood cell count include fatigue, dizziness, lightheadedness, and weight loss. People with anemia may have low energy levels and be sensitive to cold. Joint pain, abdominal swelling, and excessive bruising or bleeding after minor injuries may be symptoms of polcythemia.

Checking a RBC is usually done by means of a simple blood test. It is typically performed as part of a blood panel, which checks the levels of hormones, platelets, cells, and other substances found in the bloodstream. A full blood panel may require several vials of blood to be taken, which may be cause for some concern in people with a history of anemia. Medical professionals may choose to take samples over time, or instruct an anemic patient to consume extra nutrition and get plenty of rest and fluids before coming in for testing.


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Post 4

I knew that a high white blood cell count means you have an infection of some kind, but it seems that high red blood cell counts can indicate problems, too. My grandmother has heart disease, and because her heart can't do its job of oxygenating all her blood as well as it once did, her body produces more red blood cells to compensate.

Post 3

Dehydration can cause a red blood cell count beyond the normal range. I was working outside in the heat with one of my friends from a colder climate one day, and she collapsed from dehydration.

At the emergency room, the doctor said that her red blood cell count was high. This was because she didn't have as much fluid in her blood as she normally did, so the blood cells were more concentrated. It didn't necessarily mean that there were more of them.

Post 2

@orangey03 – I had the same condition. When you don't have enough thyroid hormones, your body isn't stimulated to make all the red blood cells it needs, so you become anemic.

I felt so incredibly tired after just walking from my chair to the bathroom and back. This was because my body couldn't get enough oxygen. It had nothing to do with breathing, though.

My red blood cells were supposed to be carrying oxygen to the rest of my body, but there just weren't enough of them to do this properly. My medication helped a great deal, though.

Post 1

I recently went to see my doctor because I had symptoms of anemia. I was cold all the time, and I felt tired even when I hadn't done anything. I also felt a bit dizzy and weak.

She said I had a low red blood cell count, which meant I was anemic. However, she said that my thyroid was to blame. It was underactive, and I had to start taking medication for it.

I really don't see the connection between the two. How can hypothyroidism cause my red blood cell count to be low?

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